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Old   March 5, 2003, 04:23
Default External flow field.
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Hi all!

I have a question. My model has long and wide external flow field. So it has so many cells. So wall has not influence on the flow field. I want to minimize flow field to decrease cell numbers. Minimized flow field has not influence on flow.

If I minimize flow field, is it influence on result?
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Old   March 5, 2003, 05:06
Default Re: External flow field.
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Hmmm...I could suggest a way to check.

You could have one model with the mesh that is as coarse (minimized, as I think you are calling it) as you want, and then have a second model with a mesh that is just slightly finer (less minimized).

If the minimized flow field has no influence on your results, then both should give you identical results.

If, however, there is significant difference between the two results, I would suggest you use the finer mesh, and repeat the checking process until you have a mesh of sufficiently resolution for the problem.
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Old   March 5, 2003, 09:43
Default Re: External flow field.
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Thank Chris.

'Minimize' mean 'shorten the length of model'. Length of original model is 2 meter and radius is 1meter. I want to shorten the length,1 or 1.5 meter. And radius 0.6 or 0.8. I think that shortened length and radius have not influence on the result.

Isn't it really influence on the result??
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Old   March 5, 2003, 10:32
Default Re: External flow field.
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hi, Moon I think Cris' testing method with a little modification is still appilcable for your question. You can create another flow field with different length (maybe as you said 1)and radius (maybe as you said 0.8) and then repeat the calculation again. After comparing the new result with the old one, it is easy for you to decide the effect of such so-call minimizing on the result. However, why not decrease the total cell number by increasing the dimension of cells nearby the boundary region where the change of flow parameters is not very vehement.
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